Plug-jack connector



Sept. 13, 1966 s, ss 3,273,105

PLUGJACK CONNECTOR Filed May 5, 1964 {5 Sheets-Sheet 2 STEPHEN L. KLASSE/V INVENTOR.

b. 7" OR/VEY Sept. 13, 1966 s. L. KLASSEN 3,273,105

' PLUG-JACK CONNECTOR Filed May 5, 1964 5 Sheets-Sheet 1 STEPHEN L. KLASSEN INVENTOR.

A on/vsr p 3, 19% s. L. KLASSEN 3,273,105

PLUG-JACK CONNECTOR Filed May 5, 1964 5 Sheets-Sheet 3 STEPHEN L. KLASSEN INVENTOR.

A TOR/V5) United States Patent 3,273,105 PLUG-JACK CONNECTOR Stephen L. Klassen, Saddle Brook, N.J., assignor to Thermo Electric Co.,, Inc., Saddle Brook, N.J., a corporation of New Jersey Filed May 5, 1964, Ser. No. 364,948 7 Claims. (Cl. 339-176) This invention relates to electrical connectors and more particularly to plug-jack connectors particularly adapted for use with thermocouple leads.

In thermocouple circuitry, accurate temperature readings are required and, therefore, it is essential that plubjack connectors be of such character and construction as to avoid the introduction of variable errors in the temperature-EMF. characteristics of the particular circuit. Toward this end, it is conventional practice to make the contact members of the connector of the same materials as those of the particular thermocouple and/or connecting leads. However, in plug-jack connectors heretofore available, the machine operations, such as milling, drilling, etc., required to produce the contact members, result in a change in the temperature-EMF. characteristic of the basic alloy. Consequently, it is difficult to match, precisely, the characteristic of the contact members and the leads that are to he connected thereto, thereby introducing a variable voltage factor into the circuit. This undesirable factor is further accentuated by temperature differences effective along the plug-jack contact members, which differences are due to the design and construction of existing connectors.

An object of this invention is the provision of a plugjack connector for use in thermocouple circuits, which connection is of simple, rugged construction and wherein the temperature-EMF. characteristics of the contact members match those of the particular thermocouple leads to be connected thereto.

An object of this invention is the provision of a plugjack connector for use in a thermocouple circuit, wherein the electrical contact members are flat strips punched from thermocouple-alloy sheets.

An object of this invention is the provision of a plugjack connector for use in a thermocouple circuit, in which the electrical contact members of the plug and the jack are flat strips made of thermocouple alloys, and in which the strips of the plug engage the cooperating strips of the jack over a relatively large surface area when the plug and jack are connected together.

An object of this invention is the provision of a thermocouple connector of the plug-jack class wherein the electrical contact members of the connector are cooperating flat strips made of thermocouple alloys and wherein the lead wires are connectable to the contact strips at points disposed within the plug and jack housings, thereby minimizing adverse effects of temperature gradients.

These and other objects and advantages of the invention will become apparent from the following description when taken with the accompanying drawings. It will be understood, however, that the drawings are for purposes of illustration and are not to be construed as defining the scope or limits of the invention, reference being had for the latter purpose to the claims appended hereto.

In the drawings wherein like reference characters denote like parts in the several views:

FIGURE 1 is an exploded, isometric view showing the upper housing section of the jack and the parts associated therewith;

FIGURE 2 is a similar view showing the matching lower housing section of the jack and the parts associated therewith;

3,273,105 Patented Sept. 13, 1966 FIGURE 3 is an isometric view showing the upper housing section of the plug and the parts associated therewith;

FIGURE 4 is a similar View showing the matching lower housing section of the plug and the parts associated therewith;

FIGURE 5 is a plan view showing the two housing sections of the jack drawn to a reduced scale, each section having the associated parts assembled thereto;

FIGURE 6 is a similar view of the two housing sections of the plug;

FIGURE 7 is an isometric view of the assembled plug and jack; and

FIGURE 8 is a longitudinal, cross-sectional view taken along the line VIII-VIII of FIGURE 7.

Reference, now, is made to FIGURE 1, wherein the upper housing section of the jack is identified by the numeral 10. Such housing section is molded of a suitable plastic and includes a semi-circular, axially-extending groove 11 intersected by a transverse recess 12 having a nominal depth greater than that of the groove. A relatively-shallow channel 13, of generally rectangular crosssection, terminates in a relatively deep circular bore 15 and a relatively deep longitudinal recess 17. Similarly, a shallow channel 14 terminates in the circular bore 16 and the recess 18. Formed in opposed corners of the housing section are locating bores 20, 21 and upstanding, integral locating pins 22, 23. Otherwise, the upper surface of the housing section is monoplanar.

A pair of leaf springs 25, 26, made of a suitable spring material, such as Phosphor bronze, are arranged to be snapped into the recesses 17, 18, respectively. It is here pointed out that these springs have a nominal length somewhat greater than that of the recesses. Consequently, the springs must be flexed slightly as the ends are forced into the associated recess. When the ends of the springs are bottomed within the associated recesses, the outer sur faces of the springs, specifically the two bends identified by the numerals 27 and 28, extend above the upper surface of the housing section, whereas the central portions of each spring are spaced from the bottom wall of the associated recesses, for purposes to be described herein below.

A hole 30 extends through the housing section and terminates in an enlarged-diarneter bore formed in the outer surface of the housing section. Such bore receives the head of a fastening screw 31. The shank of the screw 31 is provided with a peripheral groove, whereby the screw may be rotatably attached to the housing section by means of a snap ring 32.

The lower housing section of the jack is identified by the numeral 10, in FIGURE 2, to which reference now is made. This housing section matches the upper housing section in general configuration and is provided with the locating bores 20, 21' and the integral upstanding locating pins 22', 23. It will be apparent that the locating pins of one housing section will be disposed in the correspondingly located locating bores of the other housing section when the two housing sections are assembled together to form the jack.

The lower housing section 10' (FIGURE 2) is provided with a hole 30' which terminates in a hexagonal bore formedin the outer surface of the housing section. Such bore accommodates the hexagonal head of a fastening nut 35, which nut has a threaded, axial hole for receiving the threaded shank of the fastening screw 31 carried by the upper housing section (see FIGURE 1). When the shank of the nut 35 is passed through the hole 30, the end thereof is flared outwardly, thereby securing the nut to the housing section.

The lower housing section 10 (FIGURE 2), is prod vided with longitudinally-extending recesses 39, 40 for receiving the contact strips 37, 38, respectively. These contact strips are punched from sheets of thermocouple alloys corresponding to the particular thermocouple leads to be connected to a particular connector. For example, the contact strips 37, 38 may be made of iron and constantan, respectively, when the connector is designed for use in a circuit utilizing an iron-constantan thermocouple. Each Contact strip is provided with a threaded hole for receiving the terminal screws 41, 42. When the contact strips are pressed into position within the associated recesses 39, 40, the upper surfaces of the contact strips lie below the upper (mating) surface of the housing section and the forward ends of the contact strips are spaced from the front wall of the housing section by the integral lips 43, 44 formed therein. The configuration of each contact strip corresponds, generally, to the configuration of the associated recess whereby each contact strip fits snugly within its recess and, therefore, will remain in position as lead wires are connected thereto by means of the terminal screws 41, 42. Such lead wires will pass through a resilient washer 45 adapted to be seated within the transverse recess 12. The circular bores 15, 16 provide clearance areas for the terminal screws 41 and 42 in the assembled device.

The two housing sections of the jack are shown in the plan view of FIGURE 5, each housing section having the associated parts assembled thereto. Specifically, the upper housing section 10 carries the two leaf springs 25, 26 and the fastening screw 31, the latter being rotatably secured to the housing section by the snap ring 32. The lower housing section 10' carries the two contact strips 37, 38 (with the associated terminal screws 41, 42), the fastening nut and the resilient washer 45.

Reference, now, is made to FIGURES 3 and 4, wherein the two matching sections of the plug housing are identified by the numerals 50 and 50. Each housing section is provided with complementary, longitudinal recesses 51, 51' and 52, 52, for snugly receiving the contact strips 53 and 54, respectively. These contact strips are made of the same alloys as the corresponding contact strips of the jack and are provided with threaded holes for receiving the terminal screws 55 and 56. It is here pointed out that the longitudinal recesses of the two housing sections have depths equal to one-half the thickness of the contact strips. Further, the contact strips are provided with similar holes 56, 57 for snugly receiving the upstanding integral pins 58 of the upper housing section 50 and the correspondingly located pins 59 of the lower housing sec- I tion 50'. The configurations of the contact strips are such that the strips fit snugly within the associated recesses. The circular bores 60', formed in the housing section 50', provide clearance areas for the shanks of the terminal screws, whereas the similar bores 60, formed in the housing section 50, provide clearance areas for the screw heads when the two housing sections are secured together. For the latter purpose, the upper housing section 50 has a fastening screw 61 secured thereto by the snap ring 62 and the lower housing section 50 has the cooperating, hexagonal nut 63 secured thereto.

The two housing sections of the jack are shown in the plan view of FIGURE 6, each housing section having the associated parts assembled thereto. Specifically, the upper housing section 50 carries the fastening screw 61 rotatably secured thereto by the snap ring 62. The lower housing section 50' carries the two contact strips 53, 54, the fastening nut 63 and the resilient washer The complete connector is shown in the isometric view of FIGURE 7. Attention is directed to the fact that the connector is polarized, that is, the plug contact strip 54 is wider than the strip 53. The entrance openings in the jack, and the contact strips thereof, are similarly proportioned, thereby making it impossible to connect the jack and plug, improperly. The heads of the fastening screws 31 and 61 are flush with the outer surfaces of the respective upper housing sections. The hexagonal heads of the cooperating fastening nuts, not visible in this particular view, also lie flush with the other outer surfaces of the lower housing sections.

FIGURE 8 is a cross-sectional view taken along the line VIIIVIII of FIGURE 7. This view shows the wide contact strip 38, carried by the lower housing section 10' of the jack, the associated terminal screw 42 and the clearance areas provided by the aligned circular bores 15 and 16'. It Will be noted that the forward end of this contact strip is spaced from the proximate outer surface of the housing section by the integral lip 44 and that the upper surface of the contact strip is disposed above such lip. The leaf spring 25 has its ends bottomed in the rectangular recess 17 and the outer spring surfaces, defined by the two bends, are spaced from the contact strip. In actual practice, the spacing between the leaf spring and the contact strip 38 is less than the thickness of the contact strip 54 carried by the plug. Thus, as the plug is connected to the jack, the contact strip 54 slides along the cooperating contact strip 38 and flexes the leaf spring. The parts are so designed that the center of the leaf spring is at all times spaced from the bottom wall of the recess 18, thereby permitting unrestrained flexing of the spring as the contact strip 54 is fully inserted into the jack. Thus, normal variations in the manufacture of the various cooperating parts can be tolerated without the leaf spring being permanently deformed by the contact strip of the plug. Further, the double bends of the leaf spring exert pressure upon the inserted contact strip 54 along two, spaced planes, thereby maintaining the cooperating contact strips 38 and 54 in firm surface engagement with each other and resulting in a good electrical contact. The other contact strips of the plug and the jack co-act in a similar manner under the influence of the other leaf spring.

In a connector made as herein described, there is a relatively large, flat surface area of contact between the cooperating electrical contacts of the plug and the jack. This results in a very low ohmic resistance between engaged contact strips, which resistance remains constant by reason of the dual pressure areas developed by the flexed leaf springs. Further, the leaf springs serve only as a means for pressing together the engaged contact strips and are not included in the electrical circuit. This eliminates the development of thermal potentials arising by reason of a difference in the materials of which the springs and contact strips are made. Still further, the points at which the lead wires are connected to the individual contact strips lie within the plug or jack housings, and the contact strips are completely enclosed within the housings when the jack is connected to the plug. This reduces to a minimum the development of spurious potentials arising by reason of temperature gradients along the contact strips when the connector is subjected to ambient temperature changes. These features are highly desirable in connectors for use in thermocouple circuitry.

The two housing sections of the plug and the jack can be made of different colored plastics, the particular color combination serving as a code indicative of the particular thermocouple alloys of which the contact strips are made.

Having now described the invention, those skilled in this art will be able to make various changes and modifications without thereby departing from the scope and spirit of the invention as recited in the following claims.

I claim:

1. A connector jack comprising,

(a) a housing of insulating material formed of two matching housing sections removably secured together,

(b) means forming a pair of spaced openings in one end of the housing,

(0) a pair of flat contact strips carried by one housing section and longitudinally aligned with said openings, and

(d) a pair of leaf springs carried by the other housing section and longitudinally aligned with the said contact strips, each leaf spring being =bent transversely to form axially-spaced convex portions, which convex portions are spaced a predetermined distance from an associated one of said contact strips.

2. The invention as recited in claim 1, wherein the leaf springs are compressively retained in generally rectangular recesses formed in said other housing section, each spring having ends bottomed in the associated recess and a central portion spaced from the bottom wall of the recess.

3. The invention as recited in claim 1, wherein the contact strips are disposed entirely within the housing and wherein the ends of the contact strips proximate to said openings are spaced from the proximate outer wall of the housing.

4. The invention as recited in claim 3, including terminal screws threaded in holes formed at the other ends of the contact strips, and complementary bores formed in each of the housing sections and serving as clearance areas for the terminal screws.

5. The invention as recited in claim 1, 1111 combination with a plug comprising a housing of insulating material having a pair of flat contact strips extending from one end thereof, said strips being insertable into the openings formed in the jack housing and having a thickness exceeding the predetermined spacing between the said leaf springs and the associated contact strips of the jack.

6. The invention as recited in claim 5, wherein the jack housing compnises matching housing sections removably secured together, and wherein the contact strips of the jack disposed within complementary, longitudinal recesses formed in both housing sections of the jack.

7. A plug-jack connector comprising,

(a) a jack housing formed of two matching housing sections removably secured together,

(b) means forming a pair of spaced entrance openings in an end of the jack housing,

(c) a pair of flat contact strips disposed in longitudinal recesses formed in one of the jack housing sections, said strips being aligned with said entrance openings,

(d) terminal screws threaded in holes formed in each of said contact strips,

(e) a pair of leaf springs carried by the other housing section of the jack and longitudinally aligned with said contact strips, each leaf spring being compressively retained in recesses formed in such housing section and each leaf spring having a pair of axiallyspaced convex portions formed the-rein, which por tions are spaced a predetermined distance from an associated one of said contact strips,

(f) a plug housing formed of two matching housing sections removably secured together,

(g) complementary, spaced recesses formed in the two housing sections of the plug,

(h) a pair of flat contact strips disposed tlIl the said complementary recesses, and having ends extending from the jack housing, said strips being insertable into the said entrance openings of the jack and having a thickness exceeding the said predetermined distance defining the spacing between the said leaf springs and the associated contact strips, and

(i) terminal screws threaded in holes provided 4111 the contact strips of the jack, the arrangement being such that when the plug is connected to the jack, the extending ends of the plug contact strips are retained in surface contact with the associated jack contact strips by the flexed leaf springs.

References Cited by the Examiner UNITED STATES PATENTS 1,953,966 4/1934 Lynch 339-91 2,625,576 1/1953 Gilbert 339191 2,997,687 8/1961 Walter 339-191 3,229,242 1/1966 Finney et a1. 339-176 EDWARD C. ALLEN, Primary Examiner.

40 W. D. MILLER, Assistant Examiner. 

1. A CONNECTOR JACK COMPRISING, (A) A HOUSING OF INSULATING MATERIAL FORMED OF TWO MATCHING HOUSING SECTIONS REMOVABLY SECURED TO GETHER, (B) MEANS FORMING A PAIR OF SPACED OPENINGS IN ONE END OF THE HOUSING, (C) A PAIR OF FLAT CONTACT STRIPS CARRIED BY ONE HOUSING SECTION AND LONGITUDINALLY ALIGNED WITH SAID OPENINGS, AND 